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Zeek vs Security Onion: catalog facts
Zeek	Security Onion
Free The software is free under its open-source licence. Hosting, hardware and external…	Freemium The platform is free, while Onion AI features are offered through sales representatives.
macOS, Linux	Linux, Self-hosted
Protocol analysers produce semantic logs of what happened on the network rather than raw packets, and its scripting…	Complete monitoring platform installed from a single ISO Includes packet capture, detection rules and threat hunting
It produces a large volume of logs that need somewhere to go, and writing custom detections means learning…	Needs dedicated hardware or virtual machines and setup time Onion AI details are only available through sales
Downloadable app	Self-hosted, Operating system
Open source	Closed source
License: BSD-3-Clause	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.